1. Field of the Invention
The present invention is directed to a telephone voice message system that uses out-of-band signalling, that is, sends call record information in a data channel separate from the voice channel and, more particularly, to a system particularly suited for storing and forwarding messages from pay telephone users in which the information, with respect to telephone call source and destination, is transferred via an out-of-band signalling concentrator network to the voice mail system which stores the message from the pay telephone user received over a separate telephone network.
2. Description of the Related Art
In general, during a typical pay telephone message storage operation, as illustrated in FIG. 1, the pay telephone user 10, using pay telephone 12, receives a dial tone from a central office switch 14 through a pay telephone interface unit 16. When the dial tone is received the pay telephone user tone dials the destination telephone 18. During the telephone call, the pay telephone interface 16, through a line interface 20 and a computer 22, monitors the progress of the call and stores information related to the call, such as the destination telephone number, the credit card number, etc. If the computer 22 detects a busy signal or a ring no answer, computer 22 will close switch 24, thereby splitting the line, and provide the user 10 with a series of voice prompts which ask the user 10 if the user 10 wishes to leave a message for the destination telephone 18. If the user 10 responds with the appropriate tone signals and coin drops and the destination telephone 18 has not answered, the computer 22 will open switch 26 and interrupt the ongoing call through the central office switch 14 to the destination telephone 18. The computer 22 will then close switch 28 seizing the local trunk, obtain a dial tone from the central office switch 14, output appropriate coin drop tones and place a telephone call to the voice mail system 30. When the voice mail system 30 answers the call, the computer 22 will transmit call record information over the telephone lines to the voice mail system 30 using conventional dual tone multifrequency signalling (DTMF). When the call record information is transmitted over the telephone lines in the same channel as the voice signal in this manner it is called in-band signalling. The call information includes for example the telephone number of the pay telephone, the telephone number of the destination telephone, the amount of money deposited by the pay telephone user 10, or credit card number, etc. Once this call information is transmitted to the voice mail system 30, the computer closes switch 26, provides the appropriate prompts to the telephone 12 indicating to the user 10 that the user 10 should leave a message after hearing a tone and issues a tone through switch 24 to the telephone 12. The user 10 then proceeds to leave a message. When the message is complete and after the voice mail system 30 allows the user 10 to review the message if desired, the CPU 22 detects an on-hook and terminates the call by opening switches 26, 28 and 24. After a predetermined time the switch 26 is again closed to allow the pay telephone 12 to receive a dial tone from the central office 14 when the handset is lifted. Later the voice mail system 30 places a call to the destination and outputs the stored message.
The typical in-band signalling operation for a telephone service request includes at least 52 tone digits which require approximately 20 seconds. This is time during which a line through one or more central office switches are occupied and during which the voice mail system 30 is also tied to the particular pay telephone placing the call.
In the prior art, as exemplified by FIG. 1, when it was necessary to perform an administration or configuration function, such as changing the amount of money necessary to leave a message, how many rings to allow before no answer is indicated or which voice mail system to use, the field personnel typically hand carry an administration terminal to each interface 16 and change the parameters manually.